7 research outputs found
Measuring Stellar Radial Velocities with a Dispersed Fixed-Delay Interferometer
We demonstrate the ability to measure precise stellar barycentric radial
velocities with the dispersed fixed-delay interferometer technique using the
Exoplanet Tracker (ET), an instrument primarily designed for precision
differential Doppler velocity measurements using this technique. Our
barycentric radial velocities, derived from observations taken at the KPNO 2.1
meter telescope, differ from those of Nidever et al. by 0.047 km/s (rms) when
simultaneous iodine calibration is used, and by 0.120 km/s (rms) without
simultaneous iodine calibration. Our results effectively show that a Michelson
interferometer coupled to a spectrograph allows precise measurements of
barycentric radial velocities even at a modest spectral resolution of R ~ 5100.
A multi-object version of the ET instrument capable of observing ~500 stars per
night is being used at the Sloan 2.5 m telescope at Apache Point Observatory
for the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS),
a wide-field radial velocity survey for extrasolar planets around TYCHO-2 stars
in the magnitude range 7.6<V<12. In addition to precise differential
velocities, this survey will also yield precise barycentric radial velocities
for many thousands of stars using the data analysis techniques reported here.
Such a large kinematic survey at high velocity precision will be useful in
identifying the signature of accretion events in the Milky Way and
understanding local stellar kinematics in addition to discovering exoplanets,
brown dwarfs and spectroscopic binaries.Comment: 9 pages, 4 figures. Accepted for publication in Ap
Laboratory Testing of a Lyot Coronagraph Equipped with an Eighth-Order Notch Filter Image Mask
We have built a series of notch filter image masks that make the Lyot
coronagraph less susceptible to low-spatial-frequency optical aberrations. In
this paper, we present experimental results of their performance in the lab
using monochromatic light. Our tests show that these ``eighth-order'' masks are
resistant to tilt and focus alignment errors, and can generate contrast levels
of 2 x 10^-6 at 3 lambda/D and 6 x 10^-7 at 10 lambda/D without the use of
corrective optics such as deformable mirrors. This work supports recent
theoretical studies suggesting that eighth-order masks can provide the
Terrestrial Planet Finder Coronagraph with a large search area, high off-axis
throughput, and a practical requisite pointing accuracy.Comment: Accepted to ApJ. 16 pages, 7 figures, Contact [email protected]
for high resolution image
The First Extrasolar Planet Discovered with a New Generation High Throughput Doppler Instrument
We report the detection of the first extrasolar planet, ET-1 (HD 102195b),
using the Exoplanet Tracker (ET), a new generation Doppler instrument. The
planet orbits HD 102195, a young star with solar metallicity that may be part
of the local association. The planet imparts radial velocity variability to the
star with a semiamplitude of m s and a period of 4.11 days.
The planetary minimum mass () is .Comment: 42 pages, 11 figures and 5 tables, Accepted for publication in Ap